Liquid washing composition



United States Patent 2,979,466 LIQUID WASHING COMPOSITION Waclav Silherman, 160 Alte Landstrasse, Kusuacht, Zurich, Switzerland It is known to use organic washing agents of anionic, cationic and non-ionic type for the manufacture of readyfor-use washing preparations including those for use in dish-washing machines. The said washing agents are used either alone or together with inorganic builders, such as sulphates, carbonates, phosphates and silicates of the alkali metals, for the manufacture of detergents or washing agents in powder and in liquid form. The detergents manufactured in this way develop a more or less copious and stable foam in the washing vessel and, therefore, cannot be introduced into automatic dish-washing machines because the foam formed greatly impairs the efliciency of the pumps used in such machines and would reduce the water pressure in the washing and rinsing nozzles to an unpermissible extent. Those organic washing agents which are used in such low concentrations that they develop only a little foam, have insuflicient washing power. I-Iowever, as soon as their concentration in the washing liquid reaches a certain limit at which their washing power is sufficient, the development of foam becomes so great that they cannot be used in an automatic dish-Washing machine. Since the total duration of the Washing and rinsing process in an automatic dishwashing machine amounts at the most to about 90 seconds, the washing power of a low-foaming washing agent must be high. The known alkali metal salts of silicic acid, carbonic acid and phosphoric acid and mixtures made from these salts possess this property. These salts, even in relatively low concentration, impart to the washing liquid an alkalinity which is sufiicient after only a short period of contact with the dirty dishes at a temperature of 120-140 F. to bring albuminous substances into solution, to emulsify fats and to promote the dispersion of other food residues. The more valuable the said alkali metal salts are, owing to their washing power, the more do they increase the surface tension of the water in an undesirable manner and thereby promote the formation of water drops on the surface of the dishes. Reduction of the surface tension to overcome this disadvantage is effected by the addition of a wetting agent which prevents the formation of water drops on the dishes, shortens the drying process and imparts a dry sheen to the clean dishes. This wetting effect, however, has previously been obtained in liquid detergents only by adding a wetting agent separately from the actual inorganic washing agent so that two different agents had to be added in separate operations to the washing and rinsing liquid.

The invention is concerned with a liquid weakly foaming washing agent, which imparts a dry sheen and has a high washing power which is intended for use particularly, but not exclusively, in dish and like washing machines. According to the invention the washing agent contains the following constituents:

4.5-6.0% by weight sodium orthosilicate (containing about 42% Na O, 20% SiO and 38% H O). 25-35% by weight sodium metasilicate pentahydrate 2,979,466 Patented Apr. 11, 1961 The alkali metal salt of an aryl sulphonate is a hydrotropic salt. It acts as a solvent intermediary between the aqueous solution of the alkali metal salts of the silicic acid and phosphoric acid on the one hand, and the organic wetting agent which is otherwise miscible with these solutions only to a very limited extent. Preferably, sodium xylene sulphonate is used as the alkali metal salt of an aryl sulphonate. Instead of this, however, the correspondingpotassium salt can be used and also, in general, alkali metal salts of other aryl sulphonic acids which possess hydrotropic properties similar to sodium xylene sulphonate such as, for example, alkali metal salts of toluene sulphonic acid, cymene sulphonic acid, tetrahydronaphthalene sulphonic acid etc. sulphonate is, however, preferred for economic reasons. In addition to the above-mentioned purpose, the addition of the hydrotropic salt serves to maintain the alkali metals salts of the silicic and phosphoric acid which are dissolved in the necessary concentration and ratio of their contents of Na O SiO P 0 in a homogeneous and stable solution without salting out or crystallising out or formation of layers. For this reason the addition of sodium xylene sulphonate is made in the above-mentioned proportions which are greater than 12% by weight, and in accordance with the invention are 14-18% calculated on the total weight of the washing agent. The ratio between Na O, SiO and P 0 is, corresponding to the amounts of sodium orthosilicate, sodium metasilicate and potassium tripolyphosphate in the above-mentioned proportions, as Na O 2.6%-3.6% SiO 1.7%-2.3% :P O 2.43.3%.

The washing agent of the invention contains an organic wetting agent. A particularly suitable wetting agent is a mixture which consists of 65-75% by weight of an ethylene oxide-polyoxypropylene condensation product with van average molecular weight of the polyoxypropylene constituent of 1500-1800 and with an average content of polyoxyethylene of 20%; 8-12% by weight of an ethylene oxide-polyoxypropylene condensation product with an average molecular weight of the polyoxypropylene constituent of 1500-1800 and with an average content of polyoxyethylene of 10%; and 15-20% by weight of isooctyl-phenyl-polyethoxyethanol. Instead of this mixture another loW foaming Wetting agent can be used. The content of 4-6% by weight of wetting agent can only be increased or decreased to an inconsiderable extent. The following consideration will explain this. A lower addition than about 4% would require a higher concentration of the washing agent in the washing bath and a higher addition than about 6% of the washing agent could easily exceed the limit at which undesirable foam-formation occurs without the washing power of the washing liquid being increased. The indicated content of about 5% of wetting agent corresponds, when the working concentration of the washing agent is from 0.15 %-0'.3%, to an optimum working concentration of the wetting agent between 0.0075%-0.0l5%.

The washing agents of the invention are pre-eminently suitable for use in automatic dish-Washing and like machines. They have on theone hand sufiicient washing power to Wash dirty dishes clean within seconds at a temperature of -140 F. and, on the other hand, they 4 Sodium xylene is prevented and the drying time is considerably reduced and they impart to the dishes a dry sheen. A further property of the washing agents of the invention is that they do not separate into two or more layers and after long storage even at temperatures down to 23 F. they neither salt out'nor crystallise out but remain clear and homogeneous. Further, the Washing agents of the invention, although they solidify at temperatures below 23 F., always become homogeneous and clear solutions after remaining at room temperature without irreversible salting out of the individual constituents taking place. On account of these properties such liquid washing agents are suitable for being injected into the washing tank by means of automatic dosing apparatus.

The preparation of the washing agent is effected by dissolving the various constituents in Water in the given proportions. The amount of water stated should at least be present. However, more Water can be added but the washing machine must then inject more washing agent per unit of volume in the washing liquid. The water concentration of 60-70% by Weight is the optimum concentration.

Example Percent by weight Sodium orthosilic-ate (containing about 42% Na O, 20% SiO and 38% B Sodium metasilicate, pentahydrate (containing about 29% Na O, 29% SiO and 42% H O) 3 Sodium xylene sulphonate 16 Organic wetting agent consisting of: 72% by weight ethylene oxide-polyoxypropylene condensate with an average molecular weight of the polyoxypropylene constituent of 15004800 and with an average content of polyoxyethylene of 20%, 10% by weight ethylene oxide-polyoxypropylene condensate with an average molecular weight of the polyoxypropylene constituent of 1500-1800 and with an average content of polyoxyethylene of 10%, 18% by weight isooctyl-phenyl-polyethoxyethanol Potassium tripolyphosphate (containing about 47% Y P 0 6.1 Water 64.7

The sodium silicate and the sodium xylene sulphonate are dissolved by stirring in Water at a temperature of about 120 F., after which the mixture of the organic wetting agent is added. After cooling to room temperature the potassium tripolyphosphate is stirred into the solution and is finally made up with water to 100% by weight.

The liquid manufactured in this way is pre-eminently suitable as a washing agent for automatic dish washing machines and has only a slight tendency to foam and it imparts a dry sheen to the dishes. It is preferably used in a concentration of 0.l5%0.3% calculated on the washing liquid.

The liquid washing agent has a specific gravity of 1.175 at F. A solution formed by diluting 3 cc. of the washing agent with one litre of distilled water has a pH value of 10.9-11.1. 100 cc. of this solution require 4.6 cc. of N/ 10 hydrochloric acid to neutralize it.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

A liquid washing composition comprising the following constituents: 4.5-6.0% by weight of sodium orthosilicate, containing about 42% Na -O, 20% |SiO and 38% H O, 25-35% by weight of sodium metasilicate pentahydrate,

containing about 29% Na O, 29% SiO and 42% H O, 5.07.0% by weight of potassium tripolyphosphate, containing about 47% P 0 I 14-18% by weight of an alkalimetal salt of an aryl sulphonate selected from the group consisting of sodiumand potassium-salts of xylene sulphonic, toluene sulphonic, cymene sulphonic and tetrahydronaphthalene sulphonic acids, -80% by weight of water, 4.0-6.0% by weight of an organic wetting agent consisting of:

65-75% by Weight of a condensation product of ethylene oxide and polyoxypropylene with an average molecular weight of the polyoxypropylene constituent of 1,500-1,800 and with an average polyoxyethylene content of 20% 4 812% by weight ,of a condensation product of ethylene oxide and polyoxypropylene with an average molecular weight of the polyoxypropylene constituent of 1,500-1,800 and'with an average polyoxyethylene content of 10%;

15-20% by weight of isooctyl phenyl polyethoxy ethanol.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Pluronic for Home and Commercial Laundry Forrnulation, Wyandotte Chem. Corp, pp. 10-16; recd in R0. J an. 7, 1957. 

